Propellent explosive charge



' colloided nitrocellulose the charge or a portion ton . Thomson,Kilmamock, Scotld, and Ed.

tworth, New York, N. Y :1.

t to

Chemical industries ted, a cof Great Britain No Drawing. applicationApril 19,.ll9tll, 8e

, No. 389,462. In Great in 13 Claims.

This invention relates to the manufacture of propellent explosivecharges, and more particularly to the provision of gun chargescontaining a constituent adapted to reduce or eliminate muzzle flashwhich has also the property of reducing metallic fouling by action ofthe hot gases on the projectile in the firearm.

The inclusion of a small proportion of certain alkali metal salts inpropellent powder charges made from colloided nitrocellulose with orwithout the inclusion of nitroglycerine or other gelatinisers, Whetherof deterrent or non-deterrent nature, is known to have a strong eiTectin reducing the muzzle flash; and, in conditions favourable to theaction of the alkali metal salt, the flash may even be suppressedaltogether. The alkali metal salts hitherto employed for this purpose,however, have not' been possessed of the property of reducing to anyappreciable extent the metallic fouling of the rifled arms in which thepropellent charge containing them is fired. Flash reducing compoundsmoreover tend to cause a falling oil in the smokelessness of thepropellent charge.

It is known thatmetallic fouling in rifled arms is reduced by theinclusion in the propellent charge of tin, or lead, or certain alloys orcompounds of these metals. One method of employline such a metal oralloy consists in encasing thereof in the metal foil. It has also beenproposed to incorporate tin or lead compounds as ingredients during themanufacture of the propellent powder. It has been stated that the muzzleflash produced by the combustion of the powder gases is veryconsiderably reduced when tin, tin alloys, or tin compounds are presentin the propellent charge.

It is an object of our invention to provide an anti-muzzle flash type ofgun charge having a reduced tendency to cause smoke. It is also anobject of our invention to provide an anti-fouling type of gun chargehaving improved flashless characteristics. ,It is a further object ofour invention to produce an anti-fouling type of gun charge having areduced tendency to cause smoke. It is a still further object of ourinvention to provide a gun charge having an improved combination ofanti-fouling, antiefiash and smokeless characteristics. It is a stillfurther object of our invention to provide a colloided nitrocellulospropellent powder containing within its composition a compoundconferring antifouling and anti-flash characteristics chemicallycompatible with the common ingredients present in smokeless powders andwhich powder has satisfactory storage properties. A still further objectis to provide colloided nitrocellulose powders adapted for automaticfiring arms, which powders have improved firing characteristics, andwith which no muzzle attachment for the suppression of flash isrequired.

We have found that these and other objects are attained by the inclusionin the colloided nitrocellulose charge of an antimonyl compoundcontaining a combined alkali metal. The antimonyl compound is desirablyone free from halogens. The alkali metal antimonyl tartrates and theirdouble salt with other alkali metal salts are conveniently used, forinstance potassium antimonyl tartrate, commonly known as tartar emetic,lithium or sodium antimonyl tartrate, or the double salts of potassiumantimonyl tartrate with potassium bitartrate, lithium nitrate, sodiumnitrate or sodium sulphate. We prefer, how. ever, to employ tartaremetic. The colloided nitrocellulose propellent powder may be a singlebase powder or a double base powder, and may include gelatinisers of adeterrent or non-deterrent nature in its composition and may, ifdesired, be surface moderated. Any of the common deterrents such asesters, nitrocompounds, substituted ureas or urethanes of low volatilitymay be employed, for instance, di-alkyl phthalates, alkyl glycollates,alkyl tartrates, alkyl lactates, acetates of polyhydric alcohols,dinitrotoluene, mononitrotoluene, diaryl dialkyl ureas, and aryl aralkylurethanes and aryl alkyl urethanes, may

. conveniently be employed. In the case of double base powders,nitroglycerine or other liquid nitrates of polyhydric alcohols may beemployed with or without deterrents.

In putting the invention into eflectwe may introduce an antimonycompound into the propellent composition in a uniform manner during themanufacture of the latter, but a uniform distribution is not alwaysessential to the success of the invention. Thus in the case of chargesfor heavy artillery it is possible to employ as part of the charge anordinary colloided nitrocellulose propellent powder and as another partof the charge a propellent powder containing a very considerableproportion of tartar emetic. In some cases the tartar emetic may beapplied to the surface of the grains of the propellent powder therebyenabling stocks of already manufactured propellent powders to be treatedso as to improve their characteristics. In the application of-theinvention to propellent charges for small arms ammunition for machineguns and the like, the most practicable methods of introducing thetartar emetic or other antimonyl compound used involves its distributionin a more or less uniform manner throughout the powder. It may beconvemently introduced into the composition of the charge before thecommencement of the gelatinisation of the nitrocellulose.

The proportion of tartar emetic employed may conveniently be from about1% to about 5% reckoned on the weight of the total charge. Althoughincreasing the proportion of this compound increases the anti-foulingand flash reducing properties, the compound is not devoid of alltendency to increase the smoke, and it is found that between theselimits a particularly favourable combination of properties results.

The invention finds particular application in small arms ammunition foruse in machine guns and automatic rifles, the use of tartar emeticcontaining propellent powders for such ammunition effectively reducesthe muzzle flash and ensures effective removal of metallic fouling fromthe bore of the firearm, and renders unnecessary the use of muzzleattachments for masking muzzle flash. This is an advantage since theseattachments frequently give trouble owing to the accumulation of thmetallic fouling in them. The colloided nitrocellulose powderscontaining tartar emetic have storage properties as good as similarpowders from which the tartar emetic has been omitted.

The invention is illustrated by the following examples in which theparts are parts by weight.

Example 1 This example relates to the manufacture of a single base riflepowder. An amount of alcoholdehydrated nitrocellulose containing 99parts dry weight of nitrocellulose of 13.2 percent nitrogen content ismixed with 3 parts tartar emetic that has been finely ground and siftedthrough a wire sieve having 100 meshes to the limb, British standardspecification. The mixture is then colloided by the introduction inknown manner of ether containing in solution one part diphenylamine. Thecolloid is pressed through a die and out. It is then treated for solventrecovery and steeped in hot water, and is finally surfac moderated with3 parts dimethyl diphenyl urea and coated with graphite.

In a test carried out with a 0.303 inch short magazine Lee-Enfield riflein which the barrel had been considerably shortened, a rifle powder soprepared gave no flash whatever when fired; whereas a powder made insimilar fashion but from which the tartar emetic had been omitted, gavea brilliant flash. An analysis of the metallic deposits from 47 roundsof cupro-nickel jacketed bullets in 0.303 inch short magazineLee-Enfleld barrels fired with the rifle powder containing the tartaremetic and the same number of rounds flred with the powder from which ithad been omitted gave as thetotal weight of meta1 fouling 0.05 gm. and0.25 gm. respectively. The diminution in the effective bore diametercaused by the metal fouling at a point 20 inches up the barrel.

in the case of the powder containing the tartar emetic was only aboutone tenth of that observed in the case of the powder containing notartar emetic.

Example 2 This example relates to the manufacture of a single basemachine gunpowder. An amount of alcohol dehydrated nitrocellulosecontaining 99 parts dryweight of nitrocellulose of 13.2 per cent.nitrogen content is mixed with tartar emetic that sieve having 100meshes to the inch, British standard specification. The mixture is thencolloided by the introduction of ether containing in solution one partof diphenylamine. The colloid .is pressed through a die and out. It isthen treated for solvent recovery and steeped in hot water, and isfinally surface moderated with a mixture of 3.5 parts dimethyl diphenylurea and 3.5 parts dibutylphthalate and coated with graphite.

Example 3 This example relates to the manufacture of a double basemachine gun powder. 29 parts nitroglycerine are mixed with 65 parts drynitrocellulose of 13.1 per cent. nitrogen content. The resulting pasteis colloided with a solution of 6 parts diethyl diphenyl urea in aqueousacetone and 3 parts of tartar emetic are added during the incorporationof these ingredients, which is car ried out in a mixing machine at about30 C. The resulting plastic is pressed through a die into cords whichare subsequently stoved and reeled into a rope, which is finally cut tothe desired grain length. a

The advantages of the invention may be readily appreciated by thefollowing table showing the results of a test carried out in a A; inchVickers machine gun using a 664 grain bullet having a solid gildingmeta1 envelope, the number of rounds fired being 20, in which theresults obtained on firing the powder of Example 2 are compared withthose obtained on firing otherwise similar powders from the compositionof which the tartar emetic has been omitted or replaced by certainhitherto known anti-fouling and anti-flash ingredients. Y

The flrst column of the table indicates the amount of anti-flash oranti-fouling ingredient used in making the colloided nitrocellulosepowder for every 99 parts of the nitrocellulose. The second columnindicates the amount of copper found by analysis in the barrel residuesof the firearm, 'and the third column describes the appearance of theflash obtained. The fourth column indicates the order in which thevarious powders used approach freedom from smoke.

When antimonyl compounds containing a combined alkali metal other thantartar emetic are used, an amount having an antimonyl content equivalentto that of one to five parts tartar emetic may be conveniently employedfor every 100 parts of the propellent explosive.

As many. apparently widely different embodiments of the invention can.be made without departing from the spirit and scope thereof, it must beunderstood that the invention is not limited base been finely ground andsifted through a wire to to any specific embodiment except as defined inthe appended claims.

We claim:

1. A colloided nitrocellulose propellent powder gun charge comprising anantimonyl compound free from halogens and containing a combined alkalimetal. I

2. A colloided nitrocellulose propellent powder gun charge comprising analkali metal antimonyl tartrate.

3. A colloided nitrocellulose propellent powder gun charge comprisingtartar emetic.

4. A small arms propellent powder comprising colloided nitrocellulosepropellent powder having tartar emetic distributed homogeneously throughit.

5. A small arms propellent powder comprising a single base colloidednitrocellulose powder having tartar emetic distributed homogeneously guncharge comprising a double salt of an alkali 20 metal antimonyl tartrateand another alkali me al salt free from halogens.

9.- A colloided nitrocellulose propellent gt charge containing fromabout 1 to about 5 p cent. tartar emetic.

10. A colloided nitrocellulose propellent powdl gun charge having analkali metal antimon; tartrate distributed unequally through it.

11. A colloided nitrocellulose propellent powd comprising a deterrentand from about 1 to aboi 5 per cent. tartar emetic.

12. A smokeless colloided nitrocellulose prr pellent powder to thesurface of which tart: emetic has been applied.

13. A colloided nitrocellulose powder gun charg comprising an amount ofan alkali metal anti monyl tartrate equivalent in its antimonyl con tentto about 1 to about 5 per cent. tartar emeti THOMAS THOMSON. EDWARDWHITWORTH.

